XVU Audible Unit 24 Volt AC/DC Black 60mm Dia, Adjustable Vocal Sound Module 0-86 Decibels, 4 Channels, Customizable Audible Signals via SD Card

"Playlist Builder" is a free software from Schneider. It specifies MP3 files for each frame of the audio device, and configures the play order and play modes for it. At last, Playlist Builder saves all the configuration into a single playlist file and generates an Audio folder at the same time. It transfers the playlist file and audio folder into the audio device, and then it works based on specified configuration.